Abstract: Abstract: Objective To investigate the effect of triptolide (TP) on the expression of hypoxia inducible factor 1 alpha(HIF1α) and vascular endothelial growth factor (VEGF) in the human umbilical vein endothelial cells (HUVECs) under hypoxia. Methods (1) HUVECs were treated with 0, 40, 80, 160 and 320 nmol/L TP (named with hypoxia group, TP40 group, TP80 group, TP160 group and TP320 group, respectively) under the hypoxic condition (37 ℃, 5% CO2, 1% O2, 94%N2) for culturing 12 hours. Meanwhile, cells cultured under normoxia condition (without TP added) were set as the normoxia group. Western blot assay was used to detect the expression of HIF1α in each group. (2) The cells were divided into normal control group, hypoxia group and TP80 group. The immunofluorescence method was performed to detect the localization of HIF1α in cells. (3) Expressions of VEGF were detected by Western blot assay in TP80 group and hypoxia group. (4) The cells were divided into hypoxia group, TP80 group, TP80 +KF20 group (80 nmol/L TP and 20 μmol/L KC7F2), and TP80+KF30 group (80 nmol/L TP and 30 μmol/L KC7F2). After 12- hour culturing, Western blot assay was used to detect the expressions of HIF1α and VEGF in each group. Results (1) Under the normoxia condition, no HIF1α was detected in HUVECs. The expression level of HIF1α was significantly increased in TP80 group than that in hypoxia group (P < 0.05),while there was no significant change in expression of hypoxia HIF1α in TP160 group and TP320 group compared with that of hypoxic group. (2) The immunofluorescence result showed that HIF1α was mainly expressed in the nucleus. (3) The expression of VEGF was significantly increased in TP80 group than that in hypoxia group (P < 0.05). (4) After theintervention of KC7F2, HIF1α and VEGF expression levels were significantly decreased in the TP80+KF20 group and the TP80+ KF30 group than those in the TP80 group (P < 0.05). Conclusion TP can improve the expression of HIF1α and VEGF to accelerate the proliferation of endothelial cells under hypoxia condition.

Key words: triptolide, endothelial cells, hypoxia-inducible factor 1, alpha subunit, vascular endothelial growth factors, human umbilical vein endothelial cells, KC7F2, cell proliferation